Drug-resistant tuberculosis has been reported since the early days of the introduction of
chemotherapy. However, most of the evidence was limited to developed countries. In 1992,
the Third World Congress on Tuberculosis concluded that there was little recent information
on the global magnitude of multidrug-resistant tuberculosis (MDR-TB), defined as resistance
to at least isoniazid and rifampicin. Through the WHO/IUATLD Global Project on Drug-
Resistance Surveillance launched in 1994, a large number of reliable and accurate data …